Telemetric indicator of corrected angular positions



1942 A. STIEGLER TELEMETRIC INDICATOR 0F CORRECTED ANGULAR POSITIONSFiled Sept. 5, 1939 K r ll Siam/ms Zhwentor Zi/erlf ma /er .niecl Aug.iii, 11942 TELEME'RRIC INDICATOR F CORRECTED ANGULAR POSE'IIIQNS AlbertStiegler, Berlin-Marienfeldc, Germany,

assignor to Telefunken Gesellschaft fiir lDrahtlose Telegraphic m. To.Hit, Berlin, Germany, a corporation of Germany Application September 5,1939, Serial No. 293,480 in Germany September 17, 1938 (Ci. 250-1l) 4Claims.

In the installation of direction-finders, marine or aircraft, it isoften desirable to mount rotatable directional antenna systems at somedistance from the control point or observers station. In cases of thiskind, the position of the antenna may be subject to remote controlactions sent out from the observers station. In any event, the positionof the antenna must be indicated at the control point. Mechanical andelectrical remote control arrangements have been disclosed in the priorart and some of them have been tried out in practice.

A certain diinculty in this connection resides in the necessarycompensation or correction of the deviational or quadrantal error. It isknown from practice that the uncorrected radio bearing obtained fromnormal direction-finding requires correction because the directradiation, coming from a beacon whence bearings are to be taken,combines with the waves reflected from the bull or other parts of thecraft. The combined waves produce a directional indication which difiersfrom the actual beam or beacon direction by a certain quadrantal errorwhich may either be positive or negative and which is a function of thebearin angle at a given angular position of the directional antenna. Tocompensate for this error, mechanical means have been suggested in theprior art in which the bearing indication means is moved so as to lag orlead the rotation of the directional antenna by angle corresponding tothe quadrantal error.

In using directional antenna systems as heretofore known which aremechanically remote controlled, for instance, by means of a flexibleshaft, the error correction has been applied and introduced directly atthe control point. In electrical remote control such an arrangement isnot well adapted because the power required'for the actuation of theradio compensator would have to be transmitted back from the remotecontrol driving motor to the control place either mechanically orelectrically.

According to the invention, all of these drawbacks are avoided intelemetric arrangements with synchronous systems in that the powerrequired for error correction is furnished at the sendin end, andfurthermore the correction consisting of a corresponding relative shiftor rotation of a stator in respect to the cooperating rotor of atelemetric device such for example as a Selsyn motor. The telemeteredvalue, as will thus be seen. is the true bearing so that at thereceiving end no corrections will have to be inunited with each other.

troduced and only the power required for telemetric indication will haveto be transmitted.

The invention will be described by reference to the accompanying drawingin which Figure 1 is a schematic circuit diagram of one form oftelemetric device embodied in the invention, and Figures 2a and 2b areperspective views illustrating, respectively, a transmitter and receiverfor transmitting and receiving the bearing indications. Similarreference numerals will be used to indicate similar elements in theseveral figures.

In Fig. 1 is shown an embodiment of the basicidea of the invention, asynchronous system of the kind used for telemetric work in which thestators SI and S2 of the transmitter G and the receiver E are connecteddelta fashion and are The rotors R1 and R2 are connected in parallel toa source of alternating potential supply. Relative rotation of the rotorin reference to the stator at the sending end, as well known in the art,will be telemetered and indicated at the receiver with angular fidelity.Now, according to the invention, the rotor of the transmitter is turnedin synchronism with the directional antenna system A (see Fig. 2a) whilethe stator is turned in clockwise or counterclockwise directioncorresponding to the quadrantal error correction value required at eachspecific rotor position. For instance, if the relative position of thestator and the rotor as shown in the drawing corresponds to an error 1,which,

by way of example, may be assumed to be in the the true angle p=f+q.This relative angle or position of rotor and. stator is sent to thereceiver where the true bearing P will be indicated.

Fig. 2a shows a transmitter device in which a. directional antennasystem A is coaxially mounted with the rotor R1 of the transmitter andthe compensator cam K. By a crank lever system H the stator, as wellknown in the art, is turned in relation to the rotor an anglecorresponding to various quadrantal errors. The relative angularposition between rotor and stator is transmitted to the receiver E (Fig.2b) with the result that rotor R2 conjointly with pointer Z is caused toturn the true bearing angle P which is indicated on the scale Sic.

It will be understood that the arrangement hereinbefore disclosed is notto be restricted to the exemplified embodiments hereinbefore describedby reference to the drawing nor to the particular practical purposeherein mentioned. In fact this arrangement will be useful advantageouslyWherever an ang lar position is to be telemetered or transmitted to adistant point and where there is a necessity for correcting the positionas a function of an angle. It is also possible to include signal errorsof the synchronized system itself in the correction or compensator curveso that these are also eliminated.

I claim as my invention:

1. A telemetric indicating system for a radio direction finder subjectto quadrantal errors ,in which the transmitter and receiver each includean electromagnetic rotor and an electromagnetic stator, means for movingthe rotor of the transmitter in accordance with a position to beindicated, means for moving the stator of the transmitter as a functionof said quadrantal errors, and means electrically connecting thetransmitter and receiver for synchronized operation of said rotors sothat the rotor at the receiver indicates said position independent ofsaid quadrantal errors. I

2. A telemetric indicating system for indicating at a remote point radiobearings subject to the quadrantal errors of a directional antenna inwhich the telemetric transmitter and telemetric receiver each include anelectromagnetic rotor and an electromagnetic stator, means for movingthe rotor of the transmitter in accordance with the position of saiddirectional antenna, means for moving the stator of the transmitter tocor pensate for the quadrantal errors of said rectional antenna, andmeans electrically co meeting the transmitter and receiver for sychronized operation of said rotors so that t rotor of said receiverindicates said bearings i dependently of said quadrantal errors.

3. A telemetric indicating system for a rat direction finder subject toquadrantal errc in which the telemetric transmitter and receiv eachinclude an electromagnetic rotor and electromagnetic stator coaxiallymounted, mea: for moving the rotor of the transmitter in a cordance witha position to be indicated, meal including a compensating cam for movingt] stator of the transmitter as a function of sa quadrantal errors, andmeans electrically COl necting the transmitter and receiver for syichronized operation of said rotors to indicate 1 said receiver saidposition free from said quar rantal errors.

4. A telemetric indicating system for apparat1 subject to periodicallyrepeated errors in whir the transmitter and receiver of said system eacinclude an electromagnetic rotor and an electr magnetic stator, meansfor moving the rotor 1 the transmitter in accordance with the ind cationto be transmitted, means for moving ti stator of the transmitter as afunction of sai periodically repeated errors, and means eler tricallyconnecting the transmitter and receiv for synchronized operation of saidrotors so th: the rotor at the receiver gives the proper ind: cationindependent of said periodically repeate errors.

ALBERT STIEGLER.

